Ceramic faced structures and methods for manufacture thereof

Abstract

A method of adhering a ceramic facing material to an underlying substrate is disclosed. Substrates to which the concepts apply include unsupported low modulus, porous wire pads as well as low modulus, porous wire pads backed by a solid metallic form. The ceramic application techniques employed are centered around the impregnation of the regions of the pad to be ceramic coated with an underlayment coating, such as MCrAlY material, wherein the designation "M" stands for at least one of the elements from the iron cobalt and nickel group. Deep penetration of the underlayment material into the pad is achieved with a high velocity, spraying process. Ceramic material is applied over the underlayment material by conventional spraying techniques. Articles of manufacture which are suited to fabrication in accordance with the concepts disclosed herein include, but are not limited to, outer air seals, combustion chambers, and airfoils of gas turbine engines.

Having thus described typical embodiments of our invention, that which we claim as new and desire to secure by Letters Patent of the United States is: 
     
       1. A method for fabricating a ceramic faced article, comprising the steps of: forming a porous pad of metallic material to the general contour of the desired finished surface;   impregnating the porous pad with an underlayment coating of MCrAlY type material at the contoured surface of the pad to provide a roughened surface including the application of said underlayment coating at coating particle velocities on the order of four thousand feet per second (4000 fps) to attain deep impregnation of the coating into the porous pad; and   applying a ceramic material over the roughened surface of the pad to form the ceramic surfaced article.   
     
     
       2. The invention according to claim 1 wherein the step of impregnating the porous pad includes the application of MCrAlY underlayment material selected from the group consisting of nickel base alloy (NiCrAlY), cobalt base alloy (CoCrAlY), nickel cobalt base alloy (NiCoCrAlY), and iron base alloy (FeCrAlY). 
     
     
       3. The invention according to claim 2 wherein the step of impregnating the porous pad includes application of NiCrAlY material consisting essentially of 14-20 wt. % chromium;   11-13 wt. % aluminum;   0.10-0.70 wt. % yttrium;   2 wt. % maximum cobalt; and   balance nickel.   
     
     
       4. The invention according to claim 3 wherein the step of impregnating the porous pad includes the application of an equivalent depth of material within the range of four to ten thousandths of an inch (0.004-0.010 in.). 
     
     
       5. The invention according to claim 4 wherein the step of impregnating the porous pad includes the application of an equivalent depth of material of approximately five thousandths of an inch (0.005 in.). 
     
     
       6. A method for fabricating a ceramic faced article, comprising the steps of: forming a metallic substrate to the general contour of the desired ceramic facing;   bonding a porous metallic pad of nearly uniform thickness of the contoured substrate;   impregnating the porous wire pad with an underlayment coating of MCrAlY type material to provide a roughened surface over the wires of the pad including the application of said underlayment coating at coating particle velocities on the order of four thousand feet per second (4000 fps) to attain deep impregnation of the coating into the porous pad; and   applying a ceramic material over the underlayment coating to form the ceramic faced article.   
     
     
       7. The invention according to claim 6 wherein the step of impregnating the porous pad includes the application of MCrAlY underlayment material selected from the group consisting of nickel base alloy (NiCrAlY), cobalt base alloy (CoCrAlY), nickel cobalt base alloy (NiCoCrAlY) and iron base alloy (FeCrAlY). 
     
     
       8. The invention according to claim 7 wherein the step of impregnating the porous pad includes application of NiCrAlY material consisting essentially of 14-20 wt. % chromium;   11-13 wt. % aluminum;   0.10-0.70 wt. % yttrium;   2 wt. % maximum cobalt; and   balance nickel.   
     
     
       9. The invention according to claim 8 wherein the step of impregnating the porous pad includes the application of an equivalent depth of material within the range of four to ten thousandths of an inch (0.004-0.010 in.). 
     
     
       10. The invention according to claim 9 wherein the step of impregnating the porous pad includes the application of an equivalent depth of material of approximately five thousandths of an inch (0.005 in.). 
     
     
       11. A ceramic faced structure of the type suited for use in high temperature environments comprising: a porous pad of metallic material having a low modulus of elasticity which is formed to the general contour of the desired ceramic faced structure;   an underlayment coating of MCrAlY type material having an equivalent depth of greater than five thousandths of an inch (0.005 in.) but less than ten thousandths of an inch (0.010 in.) which has been impregnated into the porous pad to provide a roughened surface for adherence of the ceramic;   a ceramic material which has been applied over the underlayment coating to form the ceramic facing on the structure.   
     
     
       12. The invention according to claim 11 wherein the underlayment material is selected from the group consisting of nickel base alloy (NiCrAlY), cobalt base alloy (CoCrAlY), nickel cobalt base alloy (NiCoCrAlY), and iron base alloy (FeCrAlY). 
     
     
       13. The invention according to claim 12 wherein the underlayment material consists of a nickel base material (NiCrAlY) consisting essentially of 14-20 wt. % chromium;   11-13 wt. % aluminum;   0.10-0.70 wt. % yttrium;   2 wt. % maximum cobalt; and   balance nickel.   
     
     
       14. The invention according to claim 11 wherein said underlayment coating has been deposited by a high velocity, plasma spray process in which the velocity of underlayment material approaching the pad is on the order of four thousand feet per second (4000 fps). 
     
     
       15. The invention according to claim 12 wherein said underlayment coating has been deposited by a high velocity, plasma spray process in which the velocity of underlayment material approaching the pad is on the order of four thousand feet per second (4000 fps). 
     
     
       16. The invention according to claim 13 wherein said underlayment coating has been deposited by a high velocity, plasma spray process in which the velocity of underlayment material approaching the pad is on the order of four thousand feet per second (4000 fps). 
     
     
       17. The invention according to claim 11, 12, 13, 14, 15 or 16 wherein the porous pad of metallic material has a material density of approximately thirty-five percent (35%). 
     
     
       18. The invention according to claim 17 wherein the porous pad is fabricated of wire. 
     
     
       19. The invention according to claim 18 wherein the diameter of the wire is approximately five thousandths of an inch (0.005 in.). 
     
     
       20. The invention according to claim 19 wherein the wire is fabricated of an iron based alloy (FeCrAlY). 
     
     
       21. The invention according to claim 18 wherein the wire is fabricated of an iron based alloy (FeCrAlY). 
     
     
       22. The invention according to claim 17 wherein the metallic material is fabricated of an iron based alloy (FeCrAlY). 
     
     
       23. The invention according to claim 11, 12, 13, 14, 15 or 16 wherein the ceramic consists principally of zirconium oxide and yttrium oxide. 
     
     
       24. The invention according to claim 23 wherein the ceramic material has a composition consisting essentially of 80 wt. % zirconium oxide (ZrO 2 ); and 20 wt. % yttrium oxide (Y 2  O 3 ). 
     
     
       25. The invention according to claim 24 wherein the ceramic material has an equivalent depth within the range of twenty to one hundred thousandths of an inch (0.020-0.100 in.). 
     
     
       26. The invention according to claim 25 wherein the ceramic has an equivalent depth of sixty thousandths of an inch (0.060 in.). 
     
     
       27. The invention according to claim 23 wherein the ceramic material has an equivalent depth within the range of twenty to one hundred thousandths of an inch (0.020-0.100 in.). 
     
     
       28. The invention according to claim 27 wherein the ceramic has an equivalent depth of sixty thousandths of an inch (0.060 in.).